The invention concerns a process for monitoring the condition of the protective jacket of a burner, which consists of fireproof material, and in particular a burner lance for firing of a rotary tubular kiln for the production of cement clinker from raw powder. The invention also concerns a device for performing this process.
In a cement clinker production line, calcinated raw cement powder is converted into cement clinker in the sinter zone of a rotary tubular kiln. For the heating of the rotary tubular kiln, a long burner lance is inserted into the kiln outlet end through the stationary kiln outlet housing, at whose mouth fuels introduced into the lance burn by forming a burner flame. Instead of liquid or gaseous fuels, solid fuels are increasingly used for this purpose, in particular coal dust, but also pneumatically transportable waste fuels as secondary fuels.
The cement clinker is ejected in the red-hot condition via the stationary kiln outlet housing downwards onto a clinker cooler, usually a grid cooler, in which the cement clinker is cooled. In this process, part of the hot cooler air trapped in the kiln outlet housing is used for the combustion process as hot secondary air, which in the stationary kiln outlet housing flows from below into the rotary kiln end under flow direction. This secondary air, which is at a high temperature of 1100° C. or more, is charged with cement clinker dust. Apart from the kiln outlet housing, the burner lance in particular is exposed to mechanically abrasive and high thermo-chemical wear. The current practice of the technology is therefore to surround the meter-long lance with a protective jacket of fireproof material, as a rule a tamped fireproof compound (Brochure 8-100d “Rotary tubular kiln systems” of KHD Humboldt Wedag AG, Page 28, FIG. 3). Despite the use of such a protective jacket, the service life of a burner lance is not unlimited, even if it is equipped with its own air cooling. Damage to the fireproof material, particularly in the area of the burner tip, has previously not been able to be determined reliably enough during operation of the rotary tubular kiln. Such damage quickly leads to damage to the burner nozzle head, and thus to costly repair work to the burner. Replacement of a rotary kiln burner or its nozzle head results in undesirable interruptions in operation of the rotary kiln, and thus the operation of the complete cement clinker line, so that such a replacement should only be carried out when absolutely necessary.